1. Field of the Invention
The invention is directed to an internal gas (vapor) removal system for a fuel tank and a method of making thereof. The gas removal system of the invention is placed substantially completely inside the fuel tank to minimize hydrocarbon emissions from the fuel tank.
2. Description of Related Art
Fuel tanks for internal combustion engine-powered vehicles must have a means for removing (venting) gases from the tanks. Gases (including hydrocarbon vapors) must be vented from the tank at the time when the tank is filled with fuel and during operation of the vehicle when the fuel is not introduced into the fuel tank. It is customary in the art to use two different systems for venting gases from the fuel tank for the two aforementioned purposes. A breathing system provides a means for removing gases during filling of the tank with fuel. The heretofore-used breathing systems had to be designed in such a way that the location of an opening in the tank used to remove gases therefrom during filling (fill vent) and the size of a tube attached to the fill vent enable the tank to be filled up to its usable capacity, independent of the slope of the surface supporting the vehicle at the time it is filled with fuel.
A venting system is customarily used to provide a means for gases to escape from the fuel tank while the vehicle is in operation, i.e., at the time when fuel is not introduced into the tank.
Presently used breathing systems generally require the presence of at least one fill vent nipple (attached to the fill vent), generally placed on top of the fuel tank, to which is connected a fill vent tube. The fill vent tube has to be of a sufficient diameter to enable gases from the tank to be displaced at the same rate at which the fuel is introduced into the tank. The rate of fuel introduction into a passenger automobile may vary, but is usually about 55 liters per minute; thus, the fill vent tube used in such a vehicle has to be sized to accommodate the flow of at least about 55 liters per minute. One end of the fill vent tube is normally connected to the fill vent nipple, and the other end to the filler pipe (used to introduce fuel into the tank) to enable gases to escape through the filler pipe.
The venting system also usually requires the presence of at least one nipple ("venting nipple"), also placed on top of the fuel tank. A venting tube is attached to the venting nipple. The venting-tube removes gases from the fuel tank during operation of the vehicle, other than when the fuel tank is being filled with fuel. The venting tube of the venting system conducts gases to a charcoal canister wherein the hydrocarbons are adsorbed, and, subsequently, the gases are released to the atmosphere. The venting nipple is usually equipped with a rollover valve ("ROV") which prevents fuel from spilling out of the fuel tank in the event the vehicle is tipped over. The efficiency of the venting system should not be reduced by particular driving conditions, parking situations or fuel level in the tank. The fill vent tube and the venting tube are usually placed outside of the tank. To minimize hydrocarbon emissions, these tubes are made of a relatively impermeable plastic material, such as polyamide, which is relatively costly.
The presence of the aforementioned nipples, the rollover valve, the fill vent tube and the venting tube provides an opportunity for hydrocarbons to escape into the atmosphere.
The aforementioned basic requirements have forced car manufacturers to complicate the venting and breathing systems if the vehicle is expected to be driven under severe conditions (e.g., at severe tip angles) and/or under hot weather conditions. Conversely, the general regulatory trend for reducing fuel hydrocarbon emissions forces the manufacturers to reduce the number of accessories attached to the fuel system since each accessory, such as nipples or tubes, provides an opportunity for hydrocarbons to be emitted from the fuel tank into the atmosphere.
Attempts have been made heretofore to simplify the breathing and venting systems. For example, in French Patent 2,518,466, there is disclosed a breathing system wherein the fill vent tube is placed inside the filler pipe of the fuel tank. Although apparently not disclosed in this French Patent, in systems similar to that of this French Patent, it has been customary in the art to connect the venting tube, on the outside of the fuel tank, from the venting nipple to the top of the filler pipe. A rollover valve was then attached to the top of the filler pipe, and a separate tube from the rollover valve to the charcoal canister conducted hydrocarbon emissions from the filler pipe to the canister.
Other known systems also utilize a fill vent tube placed internally within the filler pipe. In such systems, there is no separate venting tube connecting the top of the fuel tank to the filler pipe. Instead, the fill vent tube placed within the filler pipe also serves as a venting tube. A nipple at the top of the filler pipe is equipped with a rollover valve and a tube from the rollover valve to a charcoal canister conducts all gases to the canister. However, a major problem in such a system is the obstruction of the filler pipe by fuel if the automobile is at an inclined position. The obstructed filler pipe, of course, is unable to allow gases to exit the tank.
Anhegger, U.K. Patent Application 2 105 666, discloses an installation for venting a fuel tank, such as that of a motor vehicle. The installation is formed by at least one collecting tank, placed in the interior of the fuel tank, and a vent line cooperating with the collecting tank. The installation is connected to an external line which terminates in the atmosphere or in an activated charcoal tank. However, Anhegger does not disclose a method of assembling the vent line within the tank during the fuel tank manufacturing process. Additionally, the vent line is apparently connected to a single external line terminating either in the atmosphere or in an activated charcoal canister tank.
German patent specification, DE30 40 160 A1 discloses a tank arrangement with a tank having at least two domes and having a vent line placed inside the tank. If any fuel is entrained within the vent line, the vent line is arranged in such a manner with respect to a fill nozzle that the vent line and the fill nozzle form an entrapment pump which empties the fluid from the vent line.
Various other fuel tanks and venting arrangements are disclosed by Mathey, U.S. Pat. No. 2,548,734, Brunnert, U.S. Pat. No. 4,044,913, Scheurenbrand, U.S. Pat. No. 4,450,880, Schmidt, U.S. Pat. No. 4,739,808, and French Patent application, Publication Number 2,650,227.
Sasaki et al., U.S. Pat. No. 4,714,171, disclose a method of separating a liquid from a vapor in the upper part of a fuel tank.
Japanese Laid Open Patent No. 745/1980, application number 79793/1978, discloses a method of forming a hollow article with an insert, comprising the steps of pre-blowing a molten parison of a thermoplastic resin; bringing an insert member held by a rod member in the parison into contact with an inner surface of the parison wall and blowing air into the parison.
One object of the present invention is to provide an improved method of assembling inside a blow-molded fuel tank at least one vent line for venting fuel gases from the fuel tank.
Another object of the invention is to provide an improved fuel tank system comprising a fuel tank and at least two vent lines placed substantially completely inside the fuel tank for removing gases from the fuel tank.
Additional objects of the invention will become apparent to those skilled in the art from the following description thereof.